The UserAgent property identifies the application that is
issuing the request to the server. This is a string value that should
be defined using the following format:
Application[/Version] [(Additional Information)]
For example, if the name of your application is
"MyProgram" and the current version is 2.0, then you could
specify a user agent string as follows:
MyProgram/2.0
The additional information included with the user agent string
should be enclosed in parenthesis and can include the operating
system, version and build numbers for additional components as well
as any other information that you wish to include. Multiple items
should be separated by semicolons. It is recommended that the user
agent string not be greater than 128 characters in length.